Synthesis of Fluorinated Hyperbranched Polymers and Their Use as Additives in Cationic Photopolymerization

Summary: A fluorine containing hyperbranched polymer was synthesized by modifying an aromatic‐aliphatic hyperbranched polyester with a semifluorinated alcohol via a Mitsunobu reaction and was subsequently used as an additive in cationic photopolymerization of an epoxy resin. The remaining OH groups of the fluorinated hyperbranched polymer interact with the polymeric carbocation through a chain‐transfer mechanism inducing an increase in the final epoxy conversion. The fluorinated HBP induces modification of bulk and surface properties, with an increase in T_g and surface hydrophobicity already reached at very low concentration. The HBFP additive can, therefore, protect the coatings from aggressive solvents, increases hardness, and allows the preparation of a low energy surface coating.

Synthesis of fluorinated hyperbranched polyester.     

Opening Doors to Future Electrochemical Energy Devices: The Anion‐Conducting Polyketone Polyelectrolytes

The numerous potential benefits of incorporating anion‐exchange membranes (AEMs), in place of proton‐exchange membranes (PEMs), in energy storage and conversion technologies renders their development of fundamental importance for the continued evolution of alternative energy systems. However, the widespread implementation of AEMs is currently plagued by a range of problems including lower conductivity (with respect to PEMs), poor stability, and high cost. This study reports the conversion of polyketone, one of the world's most mass produced and cheap polymers, to a new highly tuneable polymer architecture, functionalized polyketone (FPK), that demonstrates a range of excellent properties rendering it a significant prospect for AEM materials. The thermal, processing, and ion‐conducting properties of FPK are governed by the amount and nature of the newly formed N‐substituted pyrrole pendant side groups. At 80 °C, the quarternized pyridyl FPK derivative (4MPyrFPK) yields ion‐conductivities of 8.6 and 10.5 mS cm^?1 in the iodide and hydroxide forms. In addition, the hydroxide form of 4MPyr‐FPK demonstrates remarkable stability toward the typically problematic alkaline conditions. No chemical decomposition is observed to the membrane after imbibing it in KOH solution for 72 h, and furthermore, the ion‐conductivity is demonstrated to remain constant for at least 30 d at 80 °C.     

Bio‐inspired Highly Scattering Networks via Polymer Phase Separation

A common strategy to optimize whiteness in living organisms consists in using 3D random networks with dense and polydisperse scattering elements constituted by relatively low refractive index materials. Inspired by these natural architectures, a fast and scalable method to produce highly scattering porous polymer films via phase separation is developed. By varying the molecular weight of the polymer, the morphology of the porous films is modified, and therefore their scattering properties are tuned. The achieved transport mean free paths are in the micrometer range, improving the scattering strength of analogous low refractive index systems, e.g., standard white paper, by an order of magnitude. The produced porous films show a broadband reflectivity of ≈75% while only 4 µm thick. In addition, the films are flexible and can be readily index‐matched with water (i.e., they become transparent when wet), allowing for various applications such as coatings with tunable transmittance and responsive paints.     

Quality assessment of bed sediments of the Po River (Italy)

Comprehensive and contemporary evaluations of physical, chemical and toxicological endpoints have been performed on bed sediments of the Po River, the major Italian watercourse. Two extensive sampling campaigns were conducted in summer and winter low-flow conditions. Composite sediment samples were collected from ten reaches of the main river: the first was located in the upper region (ambient control), and the others downstream of the confluences of nine principal tributaries. The two sampling programs were paralleled by contemporary investigations on the macroinvertebrate community. The particle-size composition along the Po River showed a relatively uniform distribution of fine sand, a progressive downstream decrease of coarse sands and a corresponding increase of fine materials. The levels of polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), extractable organo halides (EOX), Cd, Cr, Cu, Hg, Ni, Pb and Zn were determined in sediment fine particles (< 63 microm), and showed marked changes across the ten river reaches. Their longitudinal trends, as those of organic carbon and total nitrogen, were very similar and largely independent of the survey season. Sediment quality benchmarks were used to evaluate sediment chemistry, and, although the overall level of contamination was from moderate to low, the reaches located downstream of the tributaries Dora Riparia, Dora Baltea, Lambro and Oglio were considered to be at risk. Sediments were tested for toxicity on Oncorhynchus mykiss, Ceriodaphnia dubia, Raphidocelis subcapitata and Vibrio fischeri. The toxicity tests were conducted both with sediment extracts and whole samples. Sediment extracts showed toxic potentials that were consistent with the spatial distribution of contaminants. Whole-sediment toxicity showed moderate/low effects which also included false positives and negatives. Alterations of the macroinvertebrate community were found for many kilometers downstream of Dora Riparia, and with a seasonal dependence, also in other reaches of the Italian river. Principal component analysis (PCA) was used to describe the longitudinal and temporal changes of the Po River, and allowed the selection of the most useful and discriminating indicators.     

Some considerations on the warping of marble façades: the example of Alvar Aalto’s Finland Hall in Helsinki

A scanning electron microscope study was performed on samples cored from the white-marble panels of Finland Hall’s façade which revealed considerable warping only a few years after the building’s completion. The analysis shows that granular decohesion is the most important sign of damage at the microstructural level. The presence of calcium sulphate is clearly recognisable on the façade’s surface, though it appears that chemical attack has failed to penetrate inside the material and, presumably, cannot thus be considered the only cause of decay. Following up on the results of other experimental observations that correlate warping with the degradation of bending strength, flexural tests were performed on four different qualities of white-marble, conditioned by thermal cycles in order to reproduce the damage process. The tests evidence that the four material types present very different resistance to thermal aggression: some varieties hold up very poorly, while others instead remain reliable in the long term.     

Combined heat and power plant effects on CO2 emission: Case study of the University of Perugia

In this work the CO₂ emissions due to the University of Perugia's energy needs have been evaluated. Perugia is a city set in the middle of Italy, in the ‘Umbria’ region, with a population of about 1400 000 people. The University of this city was founded in 1260 and nowadays consists of eleven Faculties with 30 000 students and about 1200 teachers. The energy needs of the University are mainly due to thermal and electrical users. In particular, the thermal consumption is strictly connected to building heating in the autumn–winter months. The reduction of CO₂ emissions is one of the main goals that developed countries have established to be achieved in the next few years, not only related to the Kyoto treated goals, but also for increasing economical and industrial production with a sustainable development concept. Carbon dioxide is not strictly a toxic substance, but makes a large contribution to the ‘greenhouse effect’ with negative repercussions for the environment. For these reasons the possibility of satisfying the University of Perugia's energy needs by the adoption of one, or more, cogeneration power plant fuelled by natural gas, opportunely located at the University, has been evaluated both in terms of energy production and of CO₂ emission reduction. This study also takes into account the experiences of the cogeneration power plant that is in operation at the Engineering Faculty of Perugia University. The results have been compared with the Regional Energetic Development Planning for evaluating the influence of the University's energy needs and emissions on the whole Region. Copyright © 2001 John Wiley & Sons, Ltd.     

Evaluation of culture media for enumeration of Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium animalis in the presence of Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus

The study compared the growth capability of probiotic (Lactobacillus acidophilus La05, Lactobacillus casei Lc01 and Bifidobacterium animalis Bb12) and non-probiotic (Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus) cultures on twenty-one culture media grouped according to selectivity: non-selective agars, selective agars without antibiotics and MRS agars containing different combinations of lithium chloride, cystein, bile salts and antibiotics. Four of these media were selected for quantitative enumeration of L. acidophilus La05, L. casei Lc01, and B. animalis Bb12. The best culture media and incubation conditions for enumeration of the probiotic cultures were: B. animalis: MRS agar with dicloxacillin, 37 °C or 42 °C, anaerobiosis; L. acidophilus: MRS agar with bile salts, 37 °C or 42 °C, aerobiosis; L. casei: MRS agar with lithium chloride and sodium propionate, 37 °C or 42 °C, aerobiosis or anaerobiosis. Plating on MRS with glucose replaced by maltose, 37 °C or 42 °C, anaerobiosis, will distinguish probiotic from non-probiotic cultures. For enumeration of each probiotic in a mixed culture, the following media and incubation conditions were recommended: B. animalis: 4ABC-MRS, 42 °C, anaerobiosis, L. acidophilus: LC medium, 42 °C, aerobiosis or anaerobiosis and L. casei: LP-MRS, 42 °C, aerobiosis or anaerobiosis. In all experiments, differences in counts using pour plating or surface plating were not significant (P ≤ 0.05).     

Assessing Copy Number of MON 810 Integrations in Commercial Seed Maize Varieties by 5′ Event-Specific Real-Time PCR Validated Method Coupled to 2^{ - \Delta \Delta CT} Analysis

The objective of the present study was to assess the applicability of the MON 810 5′ event-specific method validated by the Community Reference Laboratory for Genetically Modified Food and Feed that is commonly used for quantitative purposes. This 5′ event-specific/hmg-taxon gene real-time polymerase chain reaction (PCR) protocol coupled to analysis was the chosen approach to determine the MON 810 insert copy number per haploid genome across 26 genetically modified commercial maize varieties. Variety DK 513 containing one copy integration per haploid genome was used as calibrator in each assay. Complementary data from end-point real-time PCRs that targeted specifically the MON 810 insert were also analyzed. Global results assessed and guaranteed the genetic intactness of the transgenic integration per haploid genome for 24 out of the 26 commercial varieties studied, which showed no significant differences between values respect to the calibrator value. Conversely, two varieties showed no intact transgenic insert in their genomes. This validated analytical method was suitable for MON 810 detection and quantification purposes.     

Revealing the Role of Anchoring Groups in the Electrical Conduction Through Single‐Molecule Junctions

A combined experimental and theoretical study is presented revealing the influence of metal–molecule coupling on electronic transport through single‐molecule junctions. Transport experiments through tolane molecules attached to gold electrodes via thiol, nitro, and cyano anchoring groups are performed. By fitting the experimental current–voltage characteristics to a single‐level tunneling model, we extract both the position of the molecular orbital closest to the Fermi energy and the strength of the metal–molecule coupling. The values found for these parameters are rationalized with the help of density‐functional‐theory‐based transport calculations. In particular, these calculations show that the anchoring groups determine the junction conductance by controlling not only the strength of the coupling to the metal but also the position of the relevant molecular energy levels.